Grinding and polishing machine



y 1959 J. H. KEATING 2,896,378

GRINDING AND POLISHING MACHINE Filed Nov. 18, 1955 s Sheets-Sheet 1 FIG. 2

INVENTOR. JOHN H-KEATING UML WALM ATTORNEYS July 28, 1959 J. H. KEATING GRINDING AND PGLISHING MACHINE 6 Sheets-Sheet 2 Filed Nov. 18, 1955 FIG. 3

Km 0| T T N A E E W K H N H 0 v ATTO FIG. 8

July 28, 1959 J KEATlNG 2,896,378

. GRINDING AND POLISHING MACHINE Filed Nov. 18, 1955 6 Sheets-Sheet 3 I37 50 97 95 I02 I04 I00 I07 1N VEN TOR.

JOHN H. KEATING mwmfijmm A'TTORM Us July 28, 1959 J. H. KEATING GRINDING AND POLISHING MACHINE 6 Sheets-Sheet 4 Filed Nov. 18, 1955 FIG. ll

ZISO

INVENTOR. JOHN H. KEATENG J; H. KEATINGQ GRINDING AND POLISHING MACHINE July 2s, 1959 6 Sheets-Sheet 5 Filed Nov; 18.- 1955 FIG. l2

INVENTOR.

JOHN H. KEATING FIG. l5

ATTORNEYS July 28,1959 KEATlNG 2,896,378

GRINDING AND POLISHING MACHINE Filed Nov. 18, 1955 6 Sheets-Sheet 6 INVENTOR. JOHN H. KEATING AT TOR N E YS.

finish can be imparted is important.

Unite Aluminum Mfg. Company, Cleveland, Ohio, a corporation of Ohio Application November 18, 1955, Serial No. 547,598

10 Claims. (Cl. 51-145) This invention relates to the art of surface finishing materials after they have been initially formed to shape, and the present application is a continuation in part of copending application Serial No. 531,955 filed September 1, 1955, and now abandoned in favor of the present application.

By surface finishing is meant polishing, lbufiing, grinding and the like of articles formed such as by casting, although not limited to cast surfaces. More particularly, the invention relates to surface finishing a cast surface so that it is smooth and relatively glossy. The invention has great utility where the surface to be so treated is well defined and represents a portion only of the entire article surface and particularly where the speed-at which the In the production of large quantities of identical articles, it is important to perform the finishing operation in a minimum of time.

It is a general object of the present invention to provide a method and apparatus for surface efinishing an article by moving it with respect to a plurality of devices, each of which successively contacts the article and each of whichdevices after the first imparts a finer surface finish to the article than does the preceding one. A further object of the invention is to provide a method and apparatus by which an article to be finished is continuously rotated, and polishing devices with polishing material of progressively greater fineness are successively moved into contact with the surface that is to be polished and then withdrawn when the next moves into such con tact. Another object of the invention is to provide a rotating chuck on which an article may be mounted and two or more polishing arms adjacent to and spaced about the chuck, the arms being adapted, one at a time, to be brought into contact with the surface to be polished, one arm being moved out of contact with the article as the next arm moves into contact with the article. A still further object of the invention is to provide for surface finishing an article by rotating it rapidly and then successively bringing into contact with it moving belts coated with abrasive of progressively increasing fineness.

Other objects of the invention will become apparent from the drawings and from the following specification. The novel features forming the method and apparatus of the present invention are summarized in the claims.

Referring now to the drawings:

Figure 1 is a top plan view of a preferred form of equipment embodying the present invention;

Figure 2 is a side elevation of the machine shown in Figure 1;

Figure 3 is a skeletal section through Figure 1 showing the chuck for gripping the article, the mechanism for actuating the chuck and rotating it and certain elements of the polishing mechanism and drive therefor;

Figure 4 is a section through one of the polishing arms as shown by the lines 4-4 in Figure 1;

Figure 5 is a perspective showing the motor mounting bracket and its features of adjustment as used with one of the polishing arms;

' States Patent M 2,896,378 Patented July 28, 1959 ice Figure 6 is a perspective showing the slotted locking clamp used with the arms for carrying a. cam follower;

Figure 7 is a section through Figure 4 as indicated by the lines 7-7 thereon; Figure 8 is an illustration of one form of article that is surface finished by the method and apparatus of the present inventionin this case, as an open top cast aluminum cooking utensil;

Figure 9 is a side elevation view of another preferred form of equipment embodying the present invention; a Figure 10 is a top plan view of the equipment shown in Figure 9;

Figure 11 is an exploded perspective view, partially broken away, of one of the brackets shown in Figures 9 and 10 to support the plurality of arms mounted on the machine;

Figure 12 is a top plan view of one of the arms mounted on the machine, shown in Figures 9 and 10;

A Figure 13 is a partially sectioned side elevation of the arm shown in Figure 12;

Figure 14 is an exploded perspective view, partially broken away, of one of the yoke means used to secure the arms of the machine to the frame of the machine, shown in Figures 9 and 10;

Figure 15 is a perspective view of a substantially rec tangular article of manufacture which can be surface finished on the machine shown in Figures 9 and 10;

i t Figure 16 is a perspective view of yet another preferred embodiment of the invention adapted to abrade horizontal peripheral surfaces;

Figure 17 is a fragmentary exploded view in section of the article holding chuck, article holding clamp, and an article therebetween, as employed in the embodiment of the invention shown in Figure 16.

Fig. 18 is a view showing the work holder and drive therefor in section.

Generally the present invention permits surface finishing at lower unit cost than heretofore has been possible, together with better control of the area that is to be polished and the substantial elimination of any harm to the surface finish that is not polished, as, for instance, the inner surface of an article where it is gripped by a chuck. To this end, a single chuck is provided and the article is only gripped once. During the time that it is gripped by this chuck, multiple finishing operations are performed while the surface to be finished is positively located with respect to the device that performs each of the operations. It is thus possible for the operator to place an article on the chuck, start the surface finishing and proceed to load. the next machine, resulting in a reduction in the labor cost to be attributed to the finishing of any one article.

stood the invention may be used in surface finishing other articles of other composition. Cast aluminum cooking utensils of a given shape are made in large quantities by the so-called permanent mold system of casting. When a cast article of this type is taken from the mold, it

- has a surface finish representing the roughened condition of the casting. Such cooking utensils generally are provided at their open top with an annular lip extending around the utensil, as shown in L in Figure 8. The surface of the lip stands out from the exterior side wall of the utensil. Merging with the lip L is a pad P that is shaped and drilled to accommodate a handle by which the utensil may be gripped for use. It Will be seen that the article, shown inverted in Figure 8, tapers inwardly toward the pan or utensil bottom and that this taper extends along the surface of the lip L so that elements of the lip L, if extended, intersect the cylindrical axis of the article as elements of a cone, rather than extend parallel to the axis as would be true in the case of a cylindrical surface. As the description of the invention proceeds, it will be seen that it is well adapted for handling and finishing surfaces of this general configuration in a manner that would not be possible with equipment intended for handling cylindrical surfaces and other surfaces free of surface configurations merging with them like the pad P. It will be evident the invention is not limited to surfaces or portions of surfaces as described above, but may be used to finish a wide variety of surface shapes.

Referring now to Figures 1, 2 and 3, one preferred embodiment of the present invention embodies a base that is adapted to be mounted on suitable flooring F. The base 10 is rectangular in shape and is built up of the structural angle members 12 (Figure 3) and 13 (Figure 1) to which are secured lighter gage flat panel members 15. The resultant construction has the general shape of a cubical box surmounted at its top by a table 17 in the form of a cast plate with a downwardly extending annular lip 18 bolted at 19 to the side panels of the box.

The chuck mechanism for holding the article to be surface finished and for rotating the chuck and article thereon is best shown in Figure 3. This mechanism comprises a base bracket 20 on which is mounted an electric motor 22. The motor 22 drives through a suitable gear box 23 to rotate a stub shaft 24. The stub shaft is connected by a flexible coupling 25 to a shaft 28 extending upwardly through the table 17 above the machine. The shaft 28 is provided with an enlarged collar portion 30 that engages a housing secured to the top of the table and a seal 36 carried by the housing. Thus, the collar 30 acts as a thrust bearing, and a ball bearing 37 permits free rotation of the shaft 28 as the motor 22 is rotated.

At the upper end of the shaft 28 is a chuck 40 which generally conforms in shape to the inner surface of the article to be surface finished. To insure tight frictional engagement between the chuck and the inside of the article, two resilient neoprene rings 42 are provided. As the article designated at A is pushed down onto the chuck, the slight inside taper thereof causes it to make tight engagement with the chuck rings 42 so that the two rotate as a unit when the motor 22 is energized. In certain cases, the articles to be surface finished are not pushed into tight enough engagement with the chuck by the hand alone. In such cases, an air cylinder mounted above the pan and on the axis of the shaft 28 may be energized to push down onto the article, pushing the article onto the chuck with sufficient pressure to clamp thereon.

It will be apparent that the invention may be utilized to finish articles of different sizes and shapes. To this end the chuck 40 may be replaced from time to time with one performing the same function but of different size or shape. Thus, the chuck 40, including an enlarged collar 45 integral therewith, is clamped to a slot or flat 46 of the shaft 28 by a set screw 48. .Retraction of the set screw 4 8 permits the chuck 40, shown in Figure 3, to be removed upwardly from the shaft 28 and a different chuck to be mounted thereon in its place.

The rotation of the shaft 28 is to provide constant rotation of the article during the surface finishing operation about to be described and to this end it has been found that a rotational speed of the shaft 28 of approximately l220 r.p.m. is most satisfactory for utensils as shown in Figure 8.

As the article A on the chuck is rotated, it is engaged by three moving abrasive belts each mounted on one of of the arms shown in Figures 1 and 2. The arrangement is such that the first arm, indicated as A carries a rough finished belt and this arm makes the first contact with the work. At a predetermined time, by means hereinafter described, arm A is retracted and the second arm A moves in so that its belt, having a finer abrasive than the first, contacts the work. In the embodiment of the invention shown, the second belt is known as the oil finishing belt. Again, at a preselected time, the belt on the arm A is withdrawn from contact with the work and a third arm A moves inwardly so that its belt contacts the work to provide the final buffing operation. It will be apparent that, while three arms are shown herein, more arms may be provided if required, or one of the three arms may be eliminated, depending on the degree to which the article surface is to be treated.

The arms A A and A are each mounted on the box structure 10 on brackets 50 extending outwardly therefrom. At the outboard end of each bracket is a fixture 52 bolted to it, as shown in Figure 4. The fixture is centrally bored substantially parallel to the axis of shaft 28, as shown, to accommodate a shaft 54 that is rotatably supported in the bore in a position that may be vertically adjusted by an adjusting screw 55 and lock nut 56 as shown. It will be seen from the description thus far that the shaft 54 is freely rotatable in its supporting fixture frame 60, to which is bolted an electric motor 62, havingits shaft tiltable with respect to the shaft 54 by the mechanism shown in Figure 5. It is necessary to be able to adjust the motor so that one of the belts which it drives may in turn be tilted somewhat in its path best to meet the conical surface of the lip L, as described heretofore in connection with Figure 8. This adjustment, referring to Figure 5, is accomplished through a pair of mating pads 64 and 65 adapted to lie face to face. Four holes are provided in the pad 65 to receive four studs in the pad 64. One of these studs, indicated at 67, is mounted in a cylindrical hole 68 when the assembly is put together. The other three studs, all indicated by 69, enter corresponding slots 70 of pad 65, which slots extend as segments of a circle whose center is the opening 68. Thus, within the limitations of the lengths of the slots 70 the motor 62 may be tilted about pin 67 to an adjusted position with respect to the bracket 60 and securely locked in place by suitable nuts on the ends of the studs.

To position the belt B in actual contact with the surface to be finished, a pulley is provided (Figure 4), rotatably mounted on a pin 76 inside a U-shaped support 78. The surface configuration of the pulley 75 corresponds to the surface configuration of the article to be treated. Thus, if the lip L (Figure 8) is essentially flat, the pulley 75 will be cylindrical. If on the other hand, the lip L were concave, the pulley 75 would be convex, etc. Since the surface shape of the pulley 75 is determined by the article to be polished, suitable crown must be provided on the motor pulley and also on a second pulley in order that the belt B will stay in place. The motor pulley, indicated at 80 (Figure 4) and crowned as shown, is secured to and rotatably driven by the shaft of motor 62. The second crowned pulley is best shown in Figure l and is indicated at 85. It is mounted as close as possible to the pulley 75. 'The pulley is rotatably mounted in a support indicated at 86 and is mounted on the central tubular portion of the arm indicated at 8 8 (Figure 7). It is adjustably locked in place by a lock nut 89 that clamps glge split end 90 of the support 86 tightly to the member The tubular member 88, just described, extends toward the bracket 60 and is slidable along the portion thereof shown at is Figure 4. A flat pad on the under side of theportion 95 is bolted-as by studs 97 to the portion 60 providing a rigidassembly.

The belt B is mounted over the three pulleys, num-l normally pushed away from the pulley 80 by a compression spring 100, which spring thus provides suflicient pressure to keep thebelt tight. The spring 100 lies within the sleeve 88, which sleeve, as stated, is slidably'supported on the cylindrical portion of the member 95, such cylindricalportion being indicated at 102. This cylindrical portion is slotted as at 104 to provide a guideway for a threaded pin 105 that is carried by the sleeve 88. The function of the pin 105 is to prevent relative rotation between the sleeve 88 and the cylindrical part 102 and yet permit them to slide with respect to each other by reason of the slots 104. With this construction, the aforesaidspring 100, hearing at one end against the end of the cylindrical portion 102 and at its other end against.

an internal shoulder 107 of the sleeve 83, causes the pulleys 75 and 80 to be pushed apart within the limits permitted by the slots 104 and the belt B.

As described above, each of the arms is adapted to move inwardly to contact the article that is being surface finished. Such inward motion is effected (Figure 1) by a coil tension spring 110 secured at one end to an upstanding angle member 112 fastened to the base as shown. The other end of the spring is carried on a pin 115 secured to sleeve 88, as shown in Figure 4. With this construction, the spring 110 constantly pulls the entire arm assembly about the pivot of shaft 54 towards the axis of the shaft 28.

p The arms are held out of contact with the work to be surface finished until such time as contact is desired, this being accomplished by the use of a cam 120 (Figures 1, 2 and 3). Referring to the latterfigure, the cam is shown as a plate mounted on a gear 122 that is carried around, and free to rotate with respect to, the shaft 28 by reason of an anti-friction bearing 123, the gear hub resting on the upper portion of the collar'30, heretofore described. The gear 122 meshes with a pinion 124 driven by a motor 125 through a shaft 127. A motor is bolted to an extending portion of'the table 17, indicated at 128. Thedrive from the motor 125 is arranged so that the camplate 120 rotates very slowly, it having been found in the use of the invention here exemplified that 4 rpm. is the most satisfactory. The cam plate 120 is generally circular, as shown in Figure 1,.but is provided with a recessed portion 130 as shown.

Engagement between the cam 120 and each of the arms is effected through a cam follower or roller 135 (Figure 4) rotatably mounted on the stub shaft 136 of the element indicated generally at 137 in Figure 6. This element is centrally bored as at 140 to slide over the exterior of sleeve 88 and be clamped thereon by a locking screw and nut 141 and 142. 3

Iti'will be'seen that the rollers 135 are constantly held in contact with the edge of cam 120 by the springs 110.

However, the diameter of the enlarged portion of the cam 120 issuch that when the cam followers 135 contact it, the entire arm is held outwardly and the belt B does not make contact with the work. When, however, the slowly rotating cam moves into a position where the cam follower 135 on one arm is drawn by spring 110 into the portion 1300f the earn 120, then that arm on which it is mounted pivots around the axis of shaft 54 and that particular moving belt B contacts the lip L of an article in position on chuck 40.

gant'plate 120 and is arranged to trip a circuit once in each revolution of the cam plate by actuating a limit-switch 152 (Figure 2) to bring the operation of the cam, chuck and belts to a halt by cutting off current to their respective driving motors. It may be desirable merely to stop rotation of the cam 120 and the chuck 40 while a new article A is put in place on the chuck and leave the motors 62 and belts B in operation; it will be apparent that the wiring of the unit may be easily adapted to this type of operation if so desired.

In the operation of the method and apparatus of the present invention, the first step is to place an article A on the chuck 40 and then push the starting switch 155 to start motors 62 and drive the belts. The cam and chuck starting button, indicated at 157, is then started and as the chuck rotates, the cam plate 120 makes one complete revolution bringing in succession each of the arms A A and A into contact with the work. While stop buttons are provided, equipment is preferably brought to a halt at the end of its cycle-by operation. of the limitswitch 152 described above.

The second preferred embodiment of the invention is illustrated in Figures 9 through 15. Whereas the apparatus illustrated in Figures 1 through 8 is specifically adapted for surface finishing of cylindrical or conical objects, the second preferred embodiment is adapted to finish articles having non-circular shapes such as the rectangular cooking utensil C shown in Figure 15.

The base 10 of the second embodiment of the invention is identical to that of the frame shown in Figure 3, wherein like parts are identified by like numerals. However, the top plate or table 200 of the base 10 has been modified from that of table 17 (Figure 3) to that shown in Figure 9. This top plate 200 is shaped to provide a supporting portion 202 beneath each of the arms 204, 206 and 208 (see Figures 9 and 10), it being understood that any number of arms may be employed other than the three arms shown. Since the arms are identical, for brevity and clarity of exposition, the discussion will be primarily limited to a description of arm 204. The said arms (Figure 10) are radially disposed with respect to the Work mounting chuck 210 so that the very end 212 of each polishing belt 214 makes contact with the revolving workpiece C instead of the side 216 of the belt as employed in the first discussed embodiment of the invention.

Because the articles being polished usually have inclined side surfaces, it is necessary to pivotally incline the said arms about an axis normal to the vertical axis of the work holding chuck 210 in order that the polishing belt 214 abrades a maximum surface of the article C. To this end, a bracket 218 (Figure 11) is adapted to hold the polishing arm 204 and in turn is fitted to be slidably mounted in a base plate 220 having a lug 222 depending therefrom. As shown in Figure 11 the lower portion of the bracket 218 is provided with a pair of dove-tail legs 224 and 226 which are received in matching ways 228 and 230 formed in the base plate 220. As best shown in Figure 14, the depending lug 222 is provided with gear teeth 232 on its lower periphery to be received within a yoke bracket 234 which in turn is bolted securely to the flange portion 202 of the table 200 ex tending beyond the edge of the frame 10. It will be noted that the yoke bracket 234 contains a Wormrmember 236 to engage the teeth 232 of the lug member 222 when the lug is fitted between the opposite side members 238 and 240 of the yoke bracket. A notch 242 is cut out in the flange 202 to receive the worm member 236 flush with the flange 202 so that the flanges 244 and 246 (Figure 14) of the yoke bracket 234 may be bolted securely to the top surface of the flange 202. Matching holes are provided in the lug 222 and the side members 238 and 240 of the yoke bracket 234 to piv otably secure these members together by means of a pin 248 machined to freely fit within all three holes. It will be noted that the shank 250 of the worm member 236 is provided with 7 a square head over which a wrench may be fitted in order to rotate the worm and pivot the arm 204 about the axis of the pin 248 in a vertical plane, thereby adjusting the inclination of the polishing belt 216 with respect to the article on the work holding chuck 210.

Referring now to Figures 12 and 13 in greater detail, it will be seen that the structure of the arm 204 is similiar to that arm illustrated in Figure 4. Tension is maintained in the polishing belt by means of a spring 252 urging the motor driven pulley 254 away fromthe work engaging pulley 256 onopposite ends of the arm 204. The hollow or sleeve portionof the arm 256 which fits over the solid portion 258' of the arm 204 is square incross section to prevent a tendency for the arm to twist within the bracket 218. 'A pairof plates 260 and 262 (see Figure 11) clamp the sleeve portion 256 securely in the bracket 218 and a slot 264 is provided in the solid portion 258 through which is passed a bolt 266 to delimit the rearward movement of the solid portion of the arm by the coil spring 252 contained Within the sleeve portion of the arm and pressing rearWa-rdly on the butt end of the solid portion of the arm. The bolt 266 is provided with a square head 268- on one end to fit between the plates 260 and 262 on the upper portion, and the lower end of the bolt is provided with a square nut 268 which is slidable within the slot 270 provided beneath the sleeve 256 in the bracket 218 (see Figure 11).

A cam follower 272 (Figure 13) is secured on the forward end of the sleeve portion 256 to engage the cam plate 120. Spring 252 is quite stiff compared to spring 274 contained in the base plate 220, and its sole function is to maintain tension in the polishing belt 216. When the belt is to be removed the motor driven pulley 254 mounted on the solid portion 258 of the arm 204 is pushed inwardly toward the spring 252 thereby compressing it to shorten the overall length of the arm and make the belt readily removable.

A shoulder 276 is provided on the back edge of the base plate 220 and another shoulder 278 is provided on the front portion of the bracket 218 between the dove tail legs 224 and 226 to contain the coil spring 274 there between. An elongated bolt or shaft 280 is passed through the center of the coil 274 and threadedly through the shoulder 278 of the bracket 218 and secured therein by means of a locking dog 282. Accordingly, as the cam plate 120 revolves in coneact with the calm follower 272, bracket 218 slides forwardly or rearwardly as the contour of the cam plate 120 changes in revolving pastthe cam follower.

From the foregoing discussion of the second embodiment of the invention, it will be seen that each arm 204, 206, and 208 may be adjusted to make contact with an article C chucked or held on the work holding chuck 210 by loosening bolts 284 passing through plates 260 and 262 into the bracket 218 thereby enabling the sleeve portion 256 of the arm to be adjusted rearwardly or forwardly. The inclination of the surface of the piece being polished is accommodated by adjustment of the aforedescribed worm 236 and segment 222, enabling the arm 204 to pivot in a vertical plane.

Thus, by aligning the arm radially with respect to the axis of the spinning chuck 210 and normal to the surface of the piece C to be finished, articles of non-circular shape may be surface finished as readily as articles of cylindrical or conical shape.

As set forth more fully hereinabove, the embodiments of the invention shown in Figures 1 through 15 are adapted for surface finishing of the sidewalls of articles of manufacture such as cooking utensils and the like. Yet a third embodiment of the invention is more particularly adapted to finishing horizontal peripheral surfaces such as the lids of cooking utensils which fit over the articlespolished by the first two embodiments of the invention.

8 Referring now in greater detail to Figure 16, this embodiment of the invention comprises a frame 330 including leg members 302 fabricated from angle iron stock, and a table top 304 secured to the top portions of the legs. A motor driven shaft 306 is supported at its lower end on a cross member 308 and extends upwardly through the center of the table top 304. An article holding chuck 310 (see also Figure 17) is secured to the top end of the shaft 306, and in this particular embodiment is adapted to hold a flat dish-like article 312 such as a lid of a cook-'- ing vessel, having a top horizontal peripheral surface 314- to be polished. Because of the shallowness of this typeof article, the chucking apparatus employed in the first two discussed embodiments of the invention are not suitable for holding this article in place. Accordingly, a pressure cap 316 is provided to fit over the top of thearticle 314 and hold it securely against the chuck 310. The cap 316 is rotatably secured to the lower end of the piston 318 of a fluid cylinder 320 provided to raise and" lower the cap into place with respect to the article.

The fluid cylinder 320 is supported on a supporting arm 322 fastened to the top surface of the table top 304, and shown broken away in Figure 16 so as not to partially obscure other mechanisms of the apparatus. A motor 326 (see Figure 18) is mounted on the table top- 304 to drive the cam 328 at a predetermined speed with respect to the speed of the abrading belts, and pinion 327 mounted on an extension 329 of the motor shaft engages a gear 331 integral with the underside 333 of the cam 328.

Arm supporting brackets 330 are secured to the top surface of the table top 304 upon which are mounted belt supporting arms 332 adapted to pivot about horizontal axes. A pair of pulleys 334 and 336 are mounted on opposite ends of each armto carry a rotatable abrading belt 338 thereon. Each of the pulleys 336 is connected to intermediate driving pulleys 340 and 342 by belts 344 and 346, driven by motor 347 and arranged so as to enable the arms to pivot freely about their horizontal pivotal axes. Adjusting screw means 348 are also provided on the outer ends of the arms 332 to adjust the tension of the abrading belts 338 carried on their respective pulleys.

The cam 328 is cylindrical in shape having a cam face 350 on the upper periphery of the cylindrical body. A cam follower 352 is secured to each arm 332 and adapted to engage the cam face 350 of the cylindrical cam 328, whereby each abrading belt is sequentially brought into abrading engagement with the horizontal peripheral surface 314 of the article 312. Springs 354 connect each arm to the table top in order to maintain contact between the cam followers 352, and the cam face 350. Each revolution of the cam 328 represents one work cycle and a detent 356 is secured to the under surface. of the cam platform 333 to make engagement withthe limit switch 358 once every revolution, to stop the machine.

In operation, the fluid cylinder 320 is energized to. retract its piston 318 thereby vertically elevating the cap" 316 from the chuck 310. A workpiece 312 is seated on top of the chuck 310 and the fluid cylinder 320 is then reenergized to lower the cap 316 into pressure contact with the top surface of the workpiece. Foot switch 360 is then depressed to start the abrading belts rotating, and push button switch 362 is closed to start motors 326 and 364 to rotate the chuck 310 and the cam 328 at diiferen-- tial speeds. Foot switch 361 is provided to stop the rotation of the abrading belts. Rotation of the cam 328 permits the cam follower 352 of the coarse abrading belt arm to be first lowered into abrading contact with the surface 314 of the workpiece 312 which is to be polished. After the coarse polishing operation has been completed, the cam face 352 intercepts the coarse abrading belt cam 9 follower and'lifts it out of contact with the surface 314 of the workpiece 312. Sequentially thereafter, an intermediate coarse abrading belt is then lowered into contact with the surface 314, and finally the cam follower of the third arm lowers its finishing belt into contact with the surface 314 to apply the finishing polish to the surface.

It is to be understood that while three embodiments of the invention are shown and described hereinabove, these embodiments are by way of example only and are not to be construed in a limiting sense. Other arrangements and modifications will occur to those skilled in the art and may be resorted to without departing from the scope of the invention as defined by the appended claims.

I claim:

1. In apparatus of the class described, a frame; a vertical shaft rotatably supported thereon; an article holding chuck mounted on said shaft; motor means to rotate said shaft; a supporting bracket mounted on said frame; an arm pivotably mounted on said bracket; a plurality of pulleys carried by said arm; an abrading belt rotatably carried by the pulleys of said arm; means to move two of said pulleys away from each other, thereby to main tain tension in said belt; motor means to drive said belt; a cam follower carried by said arm; cam means rotatably mounted on the axis of said shaft; motor means to drive said-cam means independently of said shaft; and resilient means interconnecting said arm and said frame to hold said cam follower in engagement with said cam means, said cam means being so shaped as to cause said arm to move toward said chuck and engage said belt with an article on said chuck and thereafter to move said belt away from said article.

2. In apparatus of the class described, a frame; a vertical shaft rotatably supported thereon; an article holding chuck on said shaft; motor means to rotate said shaft; a plurality of supporting brackets mounted on said frame; an arm pivotably mounted on each bracket; a plurality of pulleys carried by said arm; an abrading belt carried by the pulleys of each arm; means to move two of said pulleys away from each other, thereby to maintain tension in said belt; separate motor means carried by each bracketto drive each belt independently of any other belt; a cam follower carried by each arm; cam means, rotatably mounted on the axis of said shaft; independently of said shaft; and resilient means interconnecting each arm and said frame to hold a respective cam follower in engagement with said cam means, said cam means being so shaped as to sequentially cause said arms to move toward said chuck to engage a respective belt with an article on said chuck, and thereafter to sequentially move said arms away from said chuck whereby only one belt is in contact with said chuck at any given time.

3. Belt finishing apparatus comprising a frame, an article holding chuck rotatably supported thereon; an arm shiftably carried by said frame and adapted to be moved in opposite directions toward and away from said chuck; means to shift said arm positively in one direction; resilient means to shift said arm in the other direction; motor means adjustably carried by said arm; a belt pulley carried by said motor means; an element forming part of said arm and shiftably carried thereby to move toward and away from said pulley; a second pulley carried by said element on an axis substantially parallel to the axis of said first pulley; resilient means normally acting to urge said pulleys away from each other; a'third pulley mounted on said element adjacent said second pulley and adjustable thereon to permit its axis to be tilted with respect to either of said first and second pulleys, said pulleys being arranged to support an abrading belt; and an abrading belt rotatably mounted on said pulleys adapted to finish an article carried by said chuck.

4. In apparatus of the class described, a frame; a vertical shaft rotatably supported thereon; an article holding chuck on said shaft; motor means to rotate said shaft; a plurality of supporting bracketshiounted on said frame; an arm pivotally mounted on each bracket;

a plurality of pulleys carried by said arm; an abrading belt supported by said pulleys; means to move two of said pulleys away from each other, thereby to maintain tension in said belt; separate motor means carried 'by each bracket to drive each belt independently of any other belt; a cam follower carried by each arm; cam means rotatably mounted on the axis of said shaft; motor means to drive said cam means independently of said shaft; and resilient means interconnecting each arm and said frame to hold a respective cam follower in engagement with said cam plate, said plate being so shaped as successively to cause said arms to move radially toward and away from said chuck to sequentially engage and disengage said belts with an article on said chuck.

5. The apparatus set forth in claim 4 wherein said arm comprises a first hollow member adapted to freely telescope over a second member, one of said members carrying thereon an article engaging pulley and the other of said members carrying a motor driven pulley; said first resilient means being disposed between said first and second members to urge said members apart.

6. The apparatus set forth in claim 4, wherein said arm is mounted on a bracket comprising a block slidably mounted in a base plate secured to said frame; said second resilient means being interposed therebetween to urge said arm radially toward said article holding chuck.

7. The apparatus set forth in claim 4 wherein said arm is mounted on a bracket including a base plate; a lug secured to the bottom of said base plate; a yoke secured to said frame adapted to receive said lug therebetween; gear teeth formed on said lug; aworm rotatably mounted beneath said yoke to engage said lug gear teeth; and means to rotate said Worm, whereby said arm is pivotable about an axis normal to saidvertical shaft for alignment of said arm with an article carried on said chuck.

8. Apparatus of the class described comprising: a frame; a vertical shaft rotatably supported thereon; an article positioning chuck mounted on said shaft; motor means to rotate said shaft; a supporting bracket mounted on said frame; an arm pivotally mounted on said bracket for pivotal motion about an axis substantially normal to the axis of said shaft; a plurality of pulleys carried by said arm and adapted to support an abrading belt thereon; an abrading belt rotatably mounted on said pulleys; said pulleys being rotatable about axes parallel to said first mentioned axis whereby said belt is rotatable to abrade a horizontal surface; and pressure means to engage the central top portion of said article to urge said article into pressure contact with said chuck, whereby a horizontal peripheral surface of an article is abradable by said belt.

9. The apparatus set forth in claim 8 including a cam rotatably mounted on said shaft; a cam follower secured to said arm adapted to engage the cam face of said earn, the configuration of said cam face imparting vertical movement to said cam followers, whereby said arm is pivoted at a predetermined time to engage said horizontal peripheral surface.

10. Belt finishing apparatus comprising: a frame; a vertical shaft rotatably supported thereon; an article holding chuck on said shaft; motor means to rotate said shaft a plurality of revolutions per workpiece finishing cycle; a plurality of supporting brackets mounted on said frame; an arm pivotally mounted on each bracket for pivotal motion about an axis; a plurality of pulleys carried by each arm; an abrading belt supported by the pulleys of each arm; means to rotatably drive said belts; and cam means to sequentially cause said arms to move toward and away from said chuck in predetermined 11 and non-overlapping order, whereby only one abrading 2,192,240 belt is in engagement with said chuck at any given time. 2,333,507 References Cited in the file of this patent 2,579,337 UNITED STATES PATENTS 53 2,597,180

1,787,412 Stevens H Dec. 30, 1930' 2,722,787

12 Richardson M211. 5, 1940" Hair et a1. Nov. 2, 1 943! Reaser et al. v Dec. 18,"1951 1 Reaser a a1. May 20, 1952 Hallewell et a1. Nov. s, 1955 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N00 2,896,378 July 28, 1959 John H0 Keating It is hereby certified that error appears in the printed soecification of the above numbered patent requiring correction and that the said Letters 2 Patent should readas corrected below.

Column 3, line 74, for "finished" read finishing Signed and sealed this 22nd day of March 1960,

(SEAL) Attcst:

KARL H AXLINE ROBERT C. WATSON Attesting Oificer Commissioner of Patents 

